Automobile-bumper-grinding apparatus

ABSTRACT

Presented is an automobile-bumper-grinding apparatus on which an automobile bumper may be supported while its various surfaces are being abraded to effect smoothing thereof.

United States Patent- William A. Bell [77! Balsa Ave., San Jose, Calif. 95124 805,721

Mar. 10, 1969 July 20, 1971 Inventor Appl. No. Filed Patented AU'lUMOBlLE-BUMPER-GRINDING APPARATUS 21 Claims, 11 Drawing Figs.

US. Cl 51/143, 51/234 Int. Cl ..B24b 21/16, B24b 47/04 FieldofSearcli 51/137,

[56] References Cited UNITED STATES PATENTS 2,426,764 9/1947 Czamecki 51/143 2,585,376 2/1952 Dyer etal. 51/94 2,837,877 6/1958 Andrus 51/143 Primary Examiner-Othell M. Simpson Attorney-John .l. Leavitt ABSTRACT: Presented is an automobile-bumper-grinding apparatus on which an automobile bumper may be supported while its various surfaces are being abraded to effect smoothing thereof.

PATENTEB JUL 20 an SHEET 2 UF 9 IN VENTOR. WILL /AM A. .BELL

PATENTED JUL20 I97! SHEET 3 OF 9 INVENTOR. WILL l/IM ABELL PATENTED JUL20 1971 3, 593464 SHEET u BF 9 PATENTEU JUL20 I971 SHEET 5 OF 9 INVENTOR.

WILL/4M A. BELL PATENTEU JULZO IQli SHEET 8 BF 9 INVENTOR. WILL/AM ABELL PATENTEnJulzme'r; 3 5% 464 SHEET 7 UF 9 I HG. Q

INVENTOR w/u. MM A. BELL PATENTEU JUL20 um SHEET 8 [IF 9 INVENTOR. W/L L lflM/i. .BELL

INVENTOR. W/Ll. IAMA .85 LL The automobile repair'industry has come to depend upon refurbished or rebuilt automobile bumpers that have been salvaged from wrecked automobiles. Such salvaged bumpers are straightened, repaired,yground and buffed smooth, and refinished witha protective coating such as chrome, and then once again placed in the channels of commerce.

Hereto'fore, it has been customary for workers in bumper refinishing plants to hand-hold a heavy automobile bumper while exposing its various contoured surfaces to a stationary grinding or buffing wheel. It is one of the objects of this invention to provide an apparatus on which a heavy automobile bumper may be securely mounted and which possesses the facility of varied repositioning of the bumper in relation to an abrading device, and which additionally provides the facility of varied repositioning of the abrading device in relation to the bumper being repaired.

are usually much heavier than the bumper, it is the customto fixedly mount such grinding .and buffing-devices and handhold the automobile bumper so as to apply its many contoured surfaces to the grinding or buffing wheel. Accordingly, it is another object of this invention to provide a bumper-grinding 2 DESGRIPTION OF DRAWINGS FIG. 1 is a frontelevation of the apparatus, a portion being broken awayto reduce its length.

FIG. 2 is a rear elevationalview of the apparatus, a portion being broken away to reduce its length. In FIGS. 1 and 2, a

apparatus which includes a bumper clamp means movable longitudinally along and pivotable about a longitudinal axis, whichinclu'desanabrading means'that is also pivotally movable about both a horizontal and a vertical axis, and which may be physically displaced transversely of thelongitudinal axis along which the bumper clamp means is adapted to move was to provide maximum flexibility in terms of accommodating the abrading surface of the abrading means to the many contoured surfaces of the bumper'being repaired.

It sometimes happens that the nature of the-repair to be cffected on a given bumper is so slight that-such repair may be effected with hand tools, such as portable grinding and buffing equipment .which may-be hand held. Under these circumstances, it is desirable that means he provided to securely clamp the bumper while permitting its repositioning relation to a longitudinal axis extending generally along thelong dimension of the bumper. Accordingly, it is a still further object of the invention to provide a bumper clamp device which securely clamps the bumper and which may be selectively rotated about an axis extending longitudinally of the bumper to selectively expose different surfaces of the bumper to handheld equipment.

BRIEF SUMMARY OF DISCLOSURE bumper is shown in dot-dash lines clamped in the apparatus. FIG. 3 is a plan view of the apparatus illustrated in FIG. 1.

FIG. 4 is an end elevation taken in the direction indicated by the arrow 4 in FIG. I.

FIG. 5 is an end elevation of the apparatus taken in the direction indicated by the arrow 5 in FIG. 1.

FIG. '6 is a fragmentary view partly in elevation and partly in section illustrating the main carriage and clamp means in enlarged scale.

FIG. 7' is a view similar to FIG. 6 but showing the main carriage and clamp means from the opposite end thereof. FIG. 6 is'taken in the direction indicated by the arrow 5 in FIG. 1,

while FIG. 7 is'taken in the direction indicated by the arrow 4 suspended from the auxiliary frame, and showing the abrading means in dot-dash lines in an alternate position.

FIG. 9 is a horizontal sectional view taken in the plane indicated by the line 9-9 in FIG. 8- with the abrading means removed from the auxiliary carriage.

FIG. 10 is a schematic view in perspective illustrating in full lines portions of the mainframe, main carriage, clamp means, auxiliary carriage, abrading means, and showing through application of appropriate arrows the various directions in which the parts may be moved to'accommodate the abrasive surface of the abrading means tothe different surfaces of a contoured automobile bumper, and showing in dash lines an alternate position of the main carriage.

FIG. 11 is a schematic view of the pneumatic control system for the bumper clamp means and the abrading means.

DESCRIPTION OF PREFERRED EMBODIMENT apparatus of the invention comprises a main frame designated generally by the numeral 2, a main carriage designated generally by the numeral 3, clamp means 4 pivotally mounted on the main carriage and movably mounted therewith for reciprocating movement in relation thereto and to a vertically In terms of broad inclusion, the automobile bumper grindframe. Supported above the main frame and above the clamp means within which the bumper is supported, is an abrading means including a rotary abrasive belt suspended from a movable carriage -to permit selective repositioning of the abrading means to bring the rapidly rotating abrasive belt into contact with selected surfaces of the automobile bumper.

Means are provided to drive the main carriage and bumper clamp means, and the abrading means, and. control meansare provided to control such drive means.

extending auxiliary frame 7, and more particularly a horizontally extendingcant'ilever sectionB of the auxiliary frame that extends transversely across the main frame.

Movably suspended from the horizontally extending cantilever section 8 is an auxiliary carriage 9 adapted to move transversely with respect to the main frame, and from which is movably suspended anabrading means 9 that may be pivoted simultaneously about a pair of perpendicularly related horizontal axes and a vertical axis; Each of these major components will be'described in detail and in relation to associated structure in the description which follows.

MAIN FRAME 'Ihe main frame is preferably fabricated from structural iron, and=includes a pair of elongated channel members 12, held in spaced parallel relationship by horizontal crossmembers'lJat each end, and supported in an elevated position about a supporting surface '14 by legs 16 dependingfrom each comer of the frame and from aconvenient point intermediate the ends of the frame. As illustrated in FIGS. 6 and 7, each of the elongated channel' members is provided on its upper surface with an elongatedangle bar 17 turned to form an inverted V-shaped trackwayfor purposes which will hereinafter be ex- ;plained.

MAIN CARRIAGE The main frame serves to rollably support the main carriage 3 for reciprocating movement along the length of the main frame between predetermined limits. The main carriage comprises a generally rectangular structure fabricated from structural iron, conveniently angle bars, and includes a pairof side rails 21, end rails 22, and wheels 23, having V-shaped peripheries, journaled at each comer of the carriage frame. The V- shaped peripheries of the wheels engage the inverted V- shaped trackways as illustrated best in FIGS. 6 and 7, and guide the main carriage in its reciprocating movement from one end of the main frame to the other.

Mounted on the upper surface of the main carriage frame are a pair of pedestals 24 spaced apart and extending upwardly to terminate in cantilever extensions26, on the free end of each of which is rotatably journaled a stub shaft 27. Each stub shaft is provided on one side of the pedestal with a short extension 28, while on the other side of the pedestal each stub shaft is provided with a sprocket 29. Each sprocket is connected by an appropriate chain 31 to a sprocket 32 keyed to drive shaft 33. As indicated best in FIGS. 1, 2, 3 and 10, the drive shaft extends between the pair of pedestals 24 and is rotatably journaled on both. At one end, a gear segment 34 is keyed to shaft 33 and meshes with a drive gear 36 keyed to drive shaft 37 ofa gear reduction 38 which is in turn driven by an electric motor 39. Energization of the electric motor 39 and responsive pivotal movement of the gear segment 34, with consequent pivotal movement of shaft 33 is effected in manner which will hereinafter be explained in greater detail.

BUMPER CLAMP MEANS To be of maximum utility, an automobile-bumper-grinding apparatus should be as versatile as possible with respect to the various positions in which an automobile bumper may be supported while it is being repaired or refinished. Such versatility is achieved in part by displacement of the main carriage longitudinally along the elongated trackway of the main frame. The versatility of the apparatus is increased by providing means for retaining a bumper so as to permit rotation of the bumper about its own longitudinal axis in addition to longitudinal displacement of the bumper with respect to the main frame.

To accomplish this result, clamp means designated generally by the numeral 4 are provided, the clamp means comprising a pair of generally U-shaped brackets spaced apart with each bracket including spaced and parallel arms 41 and 42 joined at their lower ends by a channel member 43 which extends longitudinally of the main frame to join the pair of spaced brackets. The spaced parallel arms 41-42 are preferably heavy metallic plates rigidly welded to the channel member 43 at their lower ends. Adjacent their upper ends, the arms 42 are rigidly welded to support shaft 27 so that when the support shaft is pivoted in either direction from the full-line position of the brackets as viewed in FIG. 6, the brackets will pivot with the support shaft as illustrated by the broken lines in FIGS. 6 and 7.

To securely clamp the bumper 44, illustrated in broken lines in FIGS. 1 and 2, on the brackets, the upper free end 46 of bracket arms 42 are provided with apair of resilient blocks 47 which cooperate with resilient blocks 48 supported on the opposite arms 41 of the brackets to resiliently clamp the bumper therebetween in a manner which will hereinafter be explained.

To clamp a bumper placed between the resilient blocks 47 and 48, the blocks must be movable relative to each other and for this purpose each block 48 is mounted on the front wall 49 of a boxlike four-sided enclosure designated generally by the numeral 51 andhaving a top wall 52 which guides on the upper end 53 of the associatedarm 41. Sidewalls 54 of'the boxlike structure guide on the side edges 56 of the arms 41 as shown best in FIGS. 1,2, 6,'and 7.

To effect transverse movement of the boxlike enclosure 51 with respect to the associated arms 4], a pneumatic cylinder designated generally by the numeral 57 is supported on each bracket arm 41 so that the movable ram 48 of each pneumatic cylinder extends through an appropriate aperture (not shown) formed in the associated bracket arm 41 and attaches at its free end to the'back side of the front wall 49 of the boxlike enclosure 51. Activation and deactivation of the pneumatic cylinder is effected through appropriate conduits 59 and 61 which connect to an appropriate source of compressed air through a valve mechanism which will hereinafter be explained in greater detail.

From the foregoing it will be seen that a bumper may be supported between the pair of brackets by placing one of the flanges of the bumper between the resilient blocks 47-48. Energization of the pneumatic cylinder 57 through appropriate manipulation of the valve effects extension of the ram 58 to bring the resilient blocks 47-48 into resilient clamping engagement with the bumper interposed therebetween.

Through appropriate'controls which will hereinafter be described, the pivotally mounted clamp means with bumper clamped therein may then be moved longitudinally of the main frame by causing the main carriage to reciprocate along the main frame, and by effecting pivotal movement of the clamp means about the axis of the support shaft 27 through selective energization of the electric motor 39.

It will thus be seen that the exposed surfaces of the bumper may be placed in any selected position. Such rotary motion of the clamp means is clearly illustrated in FIG. 10 by the directional arrow. Longitudinal movement of the main carriage with respect to the main frame is indicated in FIG. 10 by the full-line arrow for movement of the main carriage to the right as viewed in FIG. 10, and by the broken line arrow for movement of the main carriage to the left from its alternate position illustrated in FIG. 10.

To effect such movement of the main carriage longitudinally of the main frame, a drive motor 66 is provided mounted on the main frame adjacent one end, the drive motor preferably being a reversible electric motor connected through appropriate sheaves and an interconnecting belt to a gear reduction 67 the output from which is connected through a suitable chain drive 68 to a shaft 69 rotatably journaled on the main frame and provided with a sprocket 71 carrying a suitable chain the lower reach 72 of which extends the full length of the main frame and the upper reach of which is separated to provide free ends 73 and 74 connected respectively to depending brackets 76 and 77, respectively, rigidly fixed adjacent opposite ends of the main carriage frame and depending as illustrated best in FIGS. 6 and 7 to a position where the ends 73 and 74 of the upper reach of the chain may be conveniently attached to the brackets. At the right end of the main frame as viewed in FIG. 1, the chain reverses its direction on a suitable sprocket 78 as shown.

It will thus be seen that by causing rotation of the motor 66 in a direction to tension the left end of the upper reach of the chain the main carriage frame is drawn to the left as viewed in FIG. 1. Conversely, when the motor is reversed in its direction of rotation so as to tension the right end of the upper reach of the chain as viewed in FIG. 1, the main carriage frame is drawn to the right as viewed in FIG. 1. Energization of the electric motor 66 is effected through an appropriate singlepole single-throw switch 81 mounted on the main frame at about its midpoint and conveniently located so that it may be actuated by the operator of the apparatus. The switch is connected in series in a suitable circuit which includes a reversing switch 82 having a spring-pressed normally upright actuating lever 83 projecting into the path of a pair of downwardly inclined cam surfaces 86 and 87 formed on the end of adjustable rods 88 and 89, respectively, the opposite ends of which are adjustably secured to the sidewall 21 of the main carriage frame 3. The cam faces cooperate with the upwardly extending actuator lever 83 to effect reversal of the electric motor 66.

Thus, as viewed in FIG. 1, the cam surface 87 is just touching the trip lever 83 of reversing switch 82. In this position of the parts it may be assumed that the main carriage 3 is moving to the left as viewed in FIG. 1. It will be seen that it requires only a small amount of additional movement to the left. for the cam surface 87 to bear against the trip lever 83 sufficiently to trip the lever to the left as viewed in FIG. 1 and effect a reversal of the motor 66. Such reversal of the motor is effected before the end of the cam surface 87 runs off the tripped reversing switch lever 83.

As soon as reversal is effected, the main carriage reverses the direction of its movement and moves to the right as viewed in FIG. 1 until it reaches the position illustrated schematically in dash lines in FIG. at which point the cam surface 86 will engage the trip lever 83 and again effect a reversal of the electric motor 66. Such reciprocating movement of the main carriage continues until such time as the ON-OFF switch 81 is actuated to an OFF position. It will of course be apparent that because the drive motor 39 which effects rotation of the clamp means is mounted independently on the main carriage and is controlled independent of the drive means that effects longitudinal translation of the main carriage, the position of the bumper held by the clamp means may be adjusted as desired and may be effected while the main carriage is moving in either direction on the main frame. It will also be apparent that by adjustment of the bars 88-89 on opposite ends of the main carriage frame, the degree of longitudinal translation of the main carriage frame over the main frame may be controlled within variable limits.

AUXILIARY FRAME The auxiliary frame designated generally by the numeral 6 is shown best in FIGS. 1 through 5, with portions of the auxiliary frame being illustrated in FIGS. 8 and 9. The auxiliary frame includes a pair of upright posts 91, supported at their lower ends 92 on the surface 14, and are attached intermediate their ends to the longitudinal channel member 12 forming a part of the main frame. At their upper ends, the posts are rigidly secured to the associated ends of horizontally extending cantilever beams 93 and 94, shown in FIG. 8 to be I-beams but understandably capable of being formed in any suitable configuration. It has been found, for instance, that a tubular configuration is quite adequate. The upper ends of posts 91 are joined by a cross brace 96 to lend rigidity to the structure. Suitable gussets 97 are provided spanning the union between the cantilever beams 93-94 and the associated posts 91 for a similar purpose.

Rigidly mounted below the cantilever beam 94 and essentially coextensive therewith is a slide rod 98 secured at one end to the associated post by means of a suitable bolt 99, and secured at its other end to a downwardly extending bearing plate 101 fixed integrally at one end on the extreme end of the cantilever beam and depending downwardly to provide a mounting portion apertured to receive a bolt 102 threaded into the end of the slide rod 98. The slide rod is spaced below the cantilever beam as shown best in FIGS. 4 and 5 and in general lies parallel to the beam.

Spaced below cantilever beam 93 as shown best in FIGS. 4 and 9, is a relatively shorter slide rod 103 securely supported at one end adjacent the associated post 91 on a downwardly extending support plate 104 welded to the underside of cantilever beam 93. A bolt 106 makes the union of this end of the slide rod 103 to plate 104 detachable. At its other end, the slide rod 103 is similarly detachably supported on a downwardly extending support plate 107 welded to the underside of cantilever beam 93 and secured by a bolt 108 as shown. The slide rod 103 is preferably laterally spaced from slide rod 98 and is parallel to it as illustrated in FIG. 9. Additionally, as illustrated in FIG. 4, the slide rod 103 is spaced the same distance between cantilever beam 93 as slide rod 98 is spaced below cantilever beam 94. The slide rods are proportioned to provide a high degree of rigidity over their entire length so as to securely support the auxiliary carriage structure 8 as will hereinafter be described.

AUXILIARY CARRIAGE In conjunction with the rotatable and longitudinally translatable clamp means, the auxiliary carriage makes possible the application of the abrading means 9 to any selected surface of the bumper being refinished. To accomplish this purpose, the auxiliary carriage comprises a plate or platen 112 shown from opposite side edges in FIGS. 1 and 2, from opposite ends in FIGS. 4 and 5, and in plan and perspective in FIGS. 9 and 10. As illustrated in these Figures, the platen is generally triangular in configuration, having an apex end 113 provided with a pivot 114, the apex portion of the platen diverging along side edges 116 which are intercepted by an arcuate rear edge 117.

The upper and lower surfaces 118 and 119, respectively, of the platen immediately adjacent the rear edge 117 form a trackway for purposes which will hereinafter be explained. The plate is slidably supported for movement transverse to the longitudinal dimension of the main frame over which it is positioned by a pair of spaced bearing blocks 121 welded to the upper surface 118 of the platen as illustrated best in FIG. 10, and slidably disposed on the associated slide rod 98 for longitudinal translation therealong.

Adjacent its apex end the platen is similarly supported on a bearing block 122 welded to the upper surface of the platen and slidably disposed on slide rod 103. It will thus be seen that the platen may easily be slid along the slide rods 98 and 103 into the alternate positions illustrated in dot-dash lines in FIG. 9. Since the abrading means 9 is suspended below the platen it will be obvious that any lateral translation of the platen will also efl ect lateral translation of the suspended abrading means.

Lateral translation of the abrading means, without more, is not sufiicient to provide the degree of adjustability of the abrading means which is required to permit grinding or buffing of all surfaces of a bumper caught in the clamp means. To provide such flexibility, a suspension beam 126 is pivotally mounted below the platen as viewed in FIGS. 8 and 9, the left end of the suspension beam being pivotally supported on the platen by pivot 144, while the opposite end of the suspension beam is rigidly attached to a carrier plate 127 equipped with a pair of upper rollers 128 and a pair of lower rollers 129, the pairs of rollers rollably engaging the adjacent upper and lower surfaces, respectively, of the platen adjacent the rear edge 1 17.

It will thus be seen that any slight amount of lateral pressure on the suspension beam will effect pivotal movement thereof in relation to the superposed platen. Since the suspension beam is wholly dependent upon the platen for its support, it is obvious that lateral translation of the platen on the associated slide rods will carry the suspension beam with the platen to whatever position the platen is moved.

The support plate 127 to which one end of the suspension beam 126 is rigidly attached is provided at its end opposite the roller pairs 128 and 129 with a support frame designated generally by the numeral 131 and including a lower plate portion 132 from which the abrading means 9 may be suspended. At its other end, the suspension beam is provided with an upwardly extending mounting plate 133 which serves as a base for one end 134 of a pneumatic cylinder 136. The pneumatic cylinder is provided with a ram 137 extension and contraction of which is controlled through appropriate conduits 138 and 139 connected to a source of pneumatic pressure as will hereinafter be described.

ABRADING MEANS The abrading means 9 may conveniently be of the type designated Model 490-5 manufactured by the Grinding & Polishing Machinery Corporation, Indianapolis, Indiana, and catalogues describing this model are available upon request.

Briefly, the abrading means is suspended from the auxiliary carriage, andmore particularly from the mounting surface 132 supported on the suspension beam 126, through a pedestal 141, preferably cast integral with a tubular housing portion 142 having a base flange 143. The base flange forms a mount for the motor-mounting flanges 144 on the housing of an electric motor 146.

Appropriately clamped in the tubular housing 142 by a clamp 147 is a tubular housing 148 forming the outer cylinder of a pneumatic cylinder having a ram member 149 extending thereinto and extensible and retractable through the application and release of air pressure through appropriate conduits 151 and 152. As indicated best in FIG. 8, the conduits 151 and 152 are appropriately connected to a valve 153 controlled through manipulation of an appropriate handle 154.

Supported on the free end of ram 149 is a bearing block 156 which serves to rotatably support a freely rotatable wheel 157 that cooperates with a similar wheel or pulley 158 keyed to the output shaft of the motor 146. An abrasive belt 159 is arranged to work around the pulleys. Release of pressure in the pneumatic cylinder 148 through manipulation of valve control handle 154 diminishes the distance between the pulleys and facilitates application of the continuous abrasive belt. Pressurizing the pneumatic cylinder causes the pulleys to move apart, thus tensioning the belt during use.

To assist in pivotal movement of the abrading means about a horizontal axis, the tubular housing 142 is provided with a generally triangular segment 161 secured to the housing by a knob 162 threaded on an appropriate stud coaxially disposed on the axis 163. The tubular housing 142 is conveniently integral with the segment 161, and is also provided with a base 164 on which is mounted a handle 166 having a grip portion 167 on the end of which is attached a switch box 168 having a pair of pushbutton switches 169 and 171 mounted thereon.

The segment 161 is provided with a slot 172 cooperating with a knurled thumb nut 173 for selectively locking the segment to the supporting pedestal 141. To control pivotal movement of the abrading means about the substantially horizontal axis of the tubular housing 148, a strap 174 is attached to the bearing block 156 mounted on ram 149 and serves to support a handle 176 which extends upwardly and transversely away from the abrading means so that the front end of the abrading means may be pivoted by manipulation of the handle to tilt the axes of rotation of the pulleys and belt 159. Also attached to the handle, or to the strap 174, is the ram 137 of the pneumatic cylinder 136, which is effective to pivot the abrading means about the axis 163. An alternate position of the parts when pivoted about this latter horizontal axis is illustrated in dot-dash lines in H6. 8.

In use, the operator stands before the abrading means as il-' lustrated in FIG. 8. His left hand is placed on the handle 176 and his right hand on the grip 167. Pushbutton switches 169 and 171 are in a position to be actuated by thumb pressure of the right hand. Motor 146 which drives abrading belt 159 is controlled by appropriate ON and OFF switches 177. From this position the operator can control the complete operation of the apparatus as described above. To effect such control,

appropriate control means as hereinafter described are within easy reach of the operator.

CONTROL MEANS As previously indicated, with the operator standing at his work station in front of the abrading means, switch 81 which controls the initial energization of main carriage drive motor 66 is within easy reach. Additionally, electric switches 169 and 171 are within easy reach of the thumb of the right hand as it grasps grip 167 on the abrading means handle 166. These electric switches control energization of electric motor 39 connected through gear box 38 and gear segment 34 with shaft 33 which effects pivotal rotation of clamp means 4. Thus, the operator may at will vary the rotary position of the clamp means merely by manipulating the two pushbutton switches.

It should be remembered that reciprocation of the maincarriage frame on the elongated trackway of the main frame is automatic once the ON-OFF switch 81 is actuated to ON position and the trip lever 83 is tripped to initiate movement of the main carriage. Thereafter, caifi surfaces 86-87 cooperating with trip lever 83 on reversing switch 82 control automatic reciprocating movement of the main carriage.

Mounted on the main carriage, and operative to control pressurization of the pneumatic cylinders 57 on the clamp means 4 is a valve 181, controlled by a trip lever 182 manipulation of which activates or deactivates the air cylinders 57. This control circuit is schematically shown in FIG. 11. A valve body 181 is connected by a conduit 183 and appropriate filter devices and pressure gauges with a source of air under pressure (not shown).

Also connected to the source of air pressure is a footoperated valve 184 having its output ports connected by conduits 138 and 139 which, as previously discussed, control activation of the pneumatic cylinder 136, activation of which to extend the ram 137 effects pivotal movement of the abrading means about the horizontal axis 163.,The valve 184 is controlled by a foot pedal 186 which is preferably spring pressed in a direction to deactivate the pneumatic cylinder 136 through relief of pressure in conduit 138. Activation of the pneumatic cylinder 136 is effected by depressing the pedal to channel air under pressure from the source (not shown) through the valve body and pressurizing conduit 138, which admits air under pressure above the piston (not shown) in the air cylinder 136. Such air pressure is effective to cause extension of the ram 137 to effect a downward pivotal movement of the abrading means as indicated by the dot-dash lines in FIG. 8.

From the foregoing it will be apparent that to commence operation of the machine it is merely necessary for the operator to place an automobile bumper between the resilient blocks carried by the clamp means and actuate the air valve 181 to pressurize air cylinders 57 and thus clamp the bumper in fixed position with respect to the bracket arms 41. Thereafter, manipulation of main switch 81 and trip lever 83 initiaties reciprocating motion of the main carriage which carries the clamp means and bumper so that the bumper is caused to move back and forth below the abrading means.

Since the spring-pressed foot pedal 186 normally tends to elevate the abrading means into the position illustrated in full lines in FIG. 8, it is only necessary for the operator to tap the foot pedal 186 to effect pressurization of conduit 138 and extension of ram 137 to lower the forward end of the abrading means to bring the abrasive belt 159 into contact with the surface of the reciprocating bumper to be refinished. More or less pressure may be applied on the abrading means by admitting more or less air to the air cylinder 136.

Simultaneous with reciprocating motion of the bumper on the main frame, manipulation of the pushbutton switches 169 and 171 by the operator will effect pivotal motion of the bumper with respect to its longitudinal axis, thus bringing additional surfaces on the bumper into engagement with the abrasive belt 159. Additionally, by exerting differential pressures with the left and right hands, the entire abrading assembly may be caused to pivot about pivot 1 14 so as to change the angle of the abrasive belt 159 in respect to the longitudinal axis of the bumper being refinished. Concomitantly, by either pulling or pushing, the auxiliary carriage may be moved transversely with respect to the main frame to reposition the abrasive belt 159 in any selected position.

it will thus be seen that the universal movement of the components of the apparatus provides a facility for grinding and refinishing an automobile bumper not heretofore provided by conventional grinding methods and apparatus, including hand-held methods of grinding automobile bumpers. It has been found that such facility at least trebles the production capability of a worker in this industry.

Having thus described the invention, what I claim to be members in elevated position above a supporting structure;

. an auxiliary frame fixed in relation to said main frame and spaced intermediate the ends thereof, said auxiliary frame including a horizontally extending cantilever section spaced above the main frame and extending transversely with respect thereto;

c. a main carriage mounted for movement along the main frame;

an auxiliary carriage movably mounted on the cantilever section of saidauxiliary frame for movement transverse to the main frame; a e. clamp means mounted on said main carriage and including a pair of brackets pivotally mounted on the main carriage for clamping an automobile bumper therebetween; abrading means movably suspended on said auxiliary carriage and elevated above the main carriage and said clamp means to permit said main carriage and clamp means to pass thereunder;

g. drive means for driving the main carriage reciprocatingly along the main frame, for selectively rotating said clamp means about a longitudinal axis to position the bumper in relation to said abrading means, and for driving said abrading means to abrade the automobile bumper positioned thereunder; and

h. control means operable to control the drive means for said main carriage, said clamp means, and said abrading means.

2. The combination according to claim 1, in which a pair of slide rods are supported on said cantilever section to extend transversely across said main frame, and said auxiliary carriage is slidably disposed on said slide rods for movement in a transverse direction with respect to the elongated main frame.

3. The combination according to claim I, in which said auxiliary frame includes a spaced pair of vertically extending columns and said cantilever section of the auxiliary frame extends transversely from the upper end of said spaced pair of vertically extending columns.

4. The combination according to claim I, in which said auxiliary carriage includes a bearing plate portion slidably disposed on the cantilever section of said auxiliary frame for movement transverse to the main frame, and a beam portion pivotally supported on said bearing plate portion for pivotal movement in relation thereto, said abrading means being suspended from said pivoted beam portion.

5. The combination according to claim 1, in which said auxiliary carriage comprises a flat metallic plate of generally triangular configuration providing a pivot adjacent one apex and an arcuate trackway along the edge of the plate opposite said pivot, and a suspension beam pivotally supported at one end from the pivot on said flat metallic plate and rollably supported at the other end on said arcuate trackway of the flat metallic plate, said abrading means being suspended from said pivoted suspension beam.

6. The combination according to claim 1, in which said auxiliary frame includes a spaced pair of slide rods supported on the cantilever section of said auxiliary frame, and said auxiliary carriage includes bearing blocks slidably disposed on said slide rods, an elongated platen'fixed to the bearing blocks and extending transversely across said slide rods and movable therealong in a transverse direction with respect to the elongated main frame, and said abrading means is pivotally suspended from said elongated platen.

7. The combination according to claim 1, in which said clamp means are mounted on the main carriage for pivotal movement about a longitudinal axis lying parallel to the elongated main frame, and said abrading means is pivotally suspended on said auxiliary carriage to permit selective angular adjustment of said abrading means with respect to the axis of rotation of said clamp means.

8. The combination according to claim 1, in which said clamp means includes a pair of generally U-shaped brackets pivotally mounted on said main carriage and on which an automobile bumper may be cfani'ped, and means for pivotally adjusting the position of the U-shaped bracket about an axis extending parallel to the main frame. I

9. The combination according to claim 1, in which said main carriage includes a rectangular base, wheels mounted at each corner of the base and rollably disposed on said trackway of the main frame, a pair of vertically extending pedestals fixed on said main carriage, and means pivotally mounting said clamp means on the upper ends of said pair of pedestals.

10. The combination according to claim 1, in which said clamp means includes a pair of clamp brackets for supporting an automobile bumper to be clamped therein, and pneumatically operated plunger means associated with said clamp brackets and selectively operable to clamp a bumper to said clamp brackets.

11. The combination according to claim 1, in which said abrading means includes an elongated support frame the long axis of which extends generally longitudinally of the elongated main frame, a pair of pulleys at opposite ends of said elongated frame, motor means supported on said frame and drivingly connected to one of said pulleys, and an abrasive belt carried by said pulleys and operable to abrade selected sections of an automobile bumper held by said clamp means.

12. The combination according to claim I, in which said abrading means is pivotally suspended on said auxiliary carriage for selective pivotal movement of the abrading means about a horizontal axis and about a vertical axis.

13. The combination according to claim I, in which pneumatic means are provided interposed between said auxiliary carriage and said abrading means to effect pivotal movement of said abrading means about a horizontal axis.

14. The combination according to claim 1, in which said abrading means is movably suspended from said auxiliary carriage in a manner to permit simultaneous displacement of the abrading means transversely with respect to the main frame, pivotal movement of the abrading means about a horizontal axis, and pivotal movement of the abrading means about a vertical axis, to thereby facilitate adjustment of the abrading means in relation to the various contours of an automobile bumper held by said clamp means.

15. The combination according to claim 1, in which said abrading means includes an elongated selectively extensible support frame, pulleys rotatably mounted on opposite ends of said extensible support frame, a flat abrasive belt rollably supported on said pulleys, and means to effect selective extension of said support frame to effect tightening of said abrasive belt on said pulleys.

16. The combination according to claim 1, in which said drive means for driving the main carriage along the main frame includes a reversible motor mounted on the main frame, a drive sprocket on the motor, and an endless chain engaging said drive sprocket and said main carriage to effect controlled reciprocation of said main carriage when the motor is energized.

17. The combination according to claim 1, in which said drive means for driving said clamp means about a longitudinal axis to selectively position the automobile bumper clamped therein in relation to the abrading means includes a motor mounted on said main carriage, a drive sprocket on said motor, and a chain drive extending between said drive sprocket and said clamp means.

18. The combination according to claim I, in which said control means operable to control the drive means for said main carriage includes a single-pole double-throw electric switch mounted on the main frame and operatively connected to the drive means for said main carriage, and cams fixed on said main carriage positioned to actuate said reversing switch when the main carriage moves to predetermined limits in either direction to effect automatic reversal of direction of movement of the main carriage when a predetermined limit has been reached.

19. The combination according to claim 1, in which said control means operable to control pivotal movement of said 21. The combination according to claim 1, in which said control means operable to effect clamping of said clamp means on an automobile bumper supported thereon includes a source of pneumatic pressure, pneumatic ram means associated with said clamp means, conduit means connecting said source of pneumatic pressure with said ram means, and valve means disposed in said conduit means and selectively operable to pressurize said pneumatic ram means to effect clamping action of said clamp means. 

1. An automobile-bumper-grinding apparatus comprising: a. an elongated main frame including a spaced pair of rail members forming a trackway and legs supporting the rail members in elevated position above a supporting structure; b. an auxiliary frame fixed in relation to said main frame and spaced intermediate the ends thereof, said auxiliary frame including a horizontally extending cantilever section spaced above the main frame and extending transversely with respect thereto; c. a main carriage mounted for movement along the main frame; d. an auxiliary carriage movably mounted on the cantilever section of said auxiliary frame for movement transverse to the main frame; e. clamp means mounted on said main carriage and including a pair of brackets pivotally mounted on the main carriage for clamping an automobile bumper therebetween; f. abrading means movably suspended on said auxiliary carriage and elevated above the main carriage and said clamp means to permit said main carriage and clamp means to pass thereunder; g. drive means for driving the main carriage reciprocatingly along the main frame, for selectively rotating said clamp means about a longitudinal axis to position the bumper in relation to said abrading means, and for driving said abrading means to abrade the automobile bumper positioned thereunder; and h. control means operable to control the drive means for said main carriage, said clamp means, and said abrading means.
 2. The combination according to claim 1, in which a pair of slide rods are supported on said cantilever section to extend transversely across said main frame, and said auxiliary carriage is slidably disposed on said slide rods for movement in a transverse direction with respect to the elongated main frame.
 3. The combination according to claim 1, in which said auxiliary frame includes a spaced pair of vertically extending columns and said cantilever section of the auxiliary frame extends transversely from the upper end of said spaced pair of vertically extending columns.
 4. The combination according to claim 1, in which said auxiliary carriage includes a bearing plate portion slidably disposed on the cantilever section of said auxiliary frame for movement transverse to the main frame, and a beam portion pivotally supported on said bearing plate portion for pivotal movement in relation thereto, said abrading means being suspended from said pivoted beam portion.
 5. The combination according to claim 1, in which said auxiliary carriage comprises a flat metallic plate of generally triangular configuration providing a pivot adjacent one apex and an arcuate trackway along the edge of the plate opposite said pivot, and a suspension beam pivotally supported at one end from the pivot on said flat metallic plate and rollably supported at the other end on said arcuate trackway of the flat metallic plate, said abrading means being suspended from said pivoted suspension beam.
 6. The combination according to claim 1, in which said auxiliary frame includes a spaced pair of slide rods supported on the cantilever sectioN of said auxiliary frame, and said auxiliary carriage includes bearing blocks slidably disposed on said slide rods, an elongated platen fixed to the bearing blocks and extending transversely across said slide rods and movable therealong in a transverse direction with respect to the elongated main frame, and said abrading means is pivotally suspended from said elongated platen.
 7. The combination according to claim 1, in which said clamp means are mounted on the main carriage for pivotal movement about a longitudinal axis lying parallel to the elongated main frame, and said abrading means is pivotally suspended on said auxiliary carriage to permit selective angular adjustment of said abrading means with respect to the axis of rotation of said clamp means.
 8. The combination according to claim 1, in which said clamp means includes a pair of generally U-shaped brackets pivotally mounted on said main carriage and on which an automobile bumper may be clamped, and means for pivotally adjusting the position of the U-shaped bracket about an axis extending parallel to the main frame.
 9. The combination according to claim 1, in which said main carriage includes a rectangular base, wheels mounted at each corner of the base and rollably disposed on said trackway of the main frame, a pair of vertically extending pedestals fixed on said main carriage, and means pivotally mounting said clamp means on the upper ends of said pair of pedestals.
 10. The combination according to claim 1, in which said clamp means includes a pair of clamp brackets for supporting an automobile bumper to be clamped therein, and pneumatically operated plunger means associated with said clamp brackets and selectively operable to clamp a bumper to said clamp brackets.
 11. The combination according to claim 1, in which said abrading means includes an elongated support frame the long axis of which extends generally longitudinally of the elongated main frame, a pair of pulleys at opposite ends of said elongated frame, motor means supported on said frame and drivingly connected to one of said pulleys, and an abrasive belt carried by said pulleys and operable to abrade selected sections of an automobile bumper held by said clamp means.
 12. The combination according to claim 1, in which said abrading means is pivotally suspended on said auxiliary carriage for selective pivotal movement of the abrading means about a horizontal axis and about a vertical axis.
 13. The combination according to claim 1, in which pneumatic means are provided interposed between said auxiliary carriage and said abrading means to effect pivotal movement of said abrading means about a horizontal axis.
 14. The combination according to claim 1, in which said abrading means is movably suspended from said auxiliary carriage in a manner to permit simultaneous displacement of the abrading means transversely with respect to the main frame, pivotal movement of the abrading means about a horizontal axis, and pivotal movement of the abrading means about a vertical axis, to thereby facilitate adjustment of the abrading means in relation to the various contours of an automobile bumper held by said clamp means.
 15. The combination according to claim 1, in which said abrading means includes an elongated selectively extensible support frame, pulleys rotatably mounted on opposite ends of said extensible support frame, a flat abrasive belt rollably supported on said pulleys, and means to effect selective extension of said support frame to effect tightening of said abrasive belt on said pulleys.
 16. The combination according to claim 1, in which said drive means for driving the main carriage along the main frame includes a reversible motor mounted on the main frame, a drive sprocket on the motor, and an endless chain engaging said drive sprocket and said main carriage to effect controlled reciprocation of said main carriage when the motor is energized.
 17. The combination according to claim 1, in which said drive means for driving said clamp means about a longitudinal axis to selectively position the automobile bumper clamped therein in relation to the abrading means includes a motor mounted on said main carriage, a drive sprocket on said motor, and a chain drive extending between said drive sprocket and said clamp means.
 18. The combination according to claim 1, in which said control means operable to control the drive means for said main carriage includes a single-pole double-throw electric switch mounted on the main frame and operatively connected to the drive means for said main carriage, and cams fixed on said main carriage positioned to actuate said reversing switch when the main carriage moves to predetermined limits in either direction to effect automatic reversal of direction of movement of the main carriage when a predetermined limit has been reached.
 19. The combination according to claim 1, in which said control means operable to control pivotal movement of said clamp means includes a pair of single-pole single-throw electric switches supported on said auxiliary carriage and operable to effect rotation of said clamp means in opposite directions.
 20. The combination according to claim 1, in which said control means operable to effect pivotal movement of said abrading means about a horizontal axis includes a source of pneumatic pressure, a pneumatic ram operably interposed between said abrading means and said auxiliary carriage, and valve means selectively operable to pressurize said pneumatic ram to effect said pivotal movement of the abrading means.
 21. The combination according to claim 1, in which said control means operable to effect clamping of said clamp means on an automobile bumper supported thereon includes a source of pneumatic pressure, pneumatic ram means associated with said clamp means, conduit means connecting said source of pneumatic pressure with said ram means, and valve means disposed in said conduit means and selectively operable to pressurize said pneumatic ram means to effect clamping action of said clamp means. 